package com.baomidou.kisso.common.bcprov.asn1;

import java.io.IOException;

/**
 * ASN.1 TaggedObject - in ASN.1 notation this is any object preceded by
 * a [n] where n is some number - these are assumed to follow the construction
 * rules (as with sequences).
 */
public abstract class ASN1TaggedObject extends ASN1Primitive implements ASN1TaggedObjectParser {

	int tagNo;

	boolean empty = false;

	boolean explicit = true;

	ASN1Encodable obj = null;


	static public ASN1TaggedObject getInstance( ASN1TaggedObject obj, boolean explicit ) {
		if ( explicit ) {
			return (ASN1TaggedObject) obj.getObject();
		}

		throw new IllegalArgumentException("implicitly tagged tagged object");
	}


	static public ASN1TaggedObject getInstance( Object obj ) {
		if ( obj == null || obj instanceof ASN1TaggedObject ) {
			return (ASN1TaggedObject) obj;
		} else if ( obj instanceof byte[] ) {
			try {
				return ASN1TaggedObject.getInstance(fromByteArray((byte[]) obj));
			} catch ( IOException e ) {
				throw new IllegalArgumentException("failed to construct tagged object from byte[]: " + e.getMessage());
			}
		}

		throw new IllegalArgumentException("unknown object in getInstance: " + obj.getClass().getName());
	}


	/**
	 * Create a tagged object with the style given by the value of explicit.
	 * <p>
	 * If the object implements ASN1Choice the tag style will always be changed
	 * to explicit in accordance with the ASN.1 encoding rules.
	 * </p>
	 * @param explicit true if the object is explicitly tagged.
	 * @param tagNo the tag number for this object.
	 * @param obj the tagged object.
	 */
	public ASN1TaggedObject( boolean explicit, int tagNo, ASN1Encodable obj ) {
		if ( obj instanceof ASN1Choice ) {
			this.explicit = true;
		} else {
			this.explicit = explicit;
		}

		this.tagNo = tagNo;

		if ( this.explicit ) {
			this.obj = obj;
		} else {
			ASN1Primitive prim = obj.toASN1Primitive();

			if ( prim instanceof ASN1Set ) {
				ASN1Set s = null;
			}

			this.obj = obj;
		}
	}


	boolean asn1Equals( ASN1Primitive o ) {
		if ( !(o instanceof ASN1TaggedObject) ) {
			return false;
		}

		ASN1TaggedObject other = (ASN1TaggedObject) o;

		if ( tagNo != other.tagNo || empty != other.empty || explicit != other.explicit ) {
			return false;
		}

		if ( obj == null ) {
			if ( other.obj != null ) {
				return false;
			}
		} else {
			if ( !(obj.toASN1Primitive().equals(other.obj.toASN1Primitive())) ) {
				return false;
			}
		}

		return true;
	}


	public int hashCode() {
		int code = tagNo;

		// TODO: actually this is wrong - the problem is that a re-encoded
		// object may end up with a different hashCode due to implicit
		// tagging. As implicit tagging is ambiguous if a sequence is involved
		// it seems the only correct method for both equals and hashCode is to
		// compare the encodings...
		if ( obj != null ) {
			code ^= obj.hashCode();
		}

		return code;
	}


	public int getTagNo() {
		return tagNo;
	}


	/**
	 * return whether or not the object may be explicitly tagged. 
	 * <p>
	 * Note: if the object has been read from an input stream, the only
	 * time you can be sure if isExplicit is returning the true state of
	 * affairs is if it returns false. An implicitly tagged object may appear
	 * to be explicitly tagged, so you need to understand the context under
	 * which the reading was done as well, see getObject below.
	 */
	public boolean isExplicit() {
		return explicit;
	}


	public boolean isEmpty() {
		return empty;
	}


	/**
	 * return whatever was following the tag.
	 * <p>
	 * Note: tagged objects are generally context dependent if you're
	 * trying to extract a tagged object you should be going via the
	 * appropriate getInstance method.
	 */
	public ASN1Primitive getObject() {
		if ( obj != null ) {
			return obj.toASN1Primitive();
		}

		return null;
	}


	/**
	 * Return the object held in this tagged object as a parser assuming it has
	 * the type of the passed in tag. If the object doesn't have a parser
	 * associated with it, the base object is returned.
	 */
	public ASN1Encodable getObjectParser( int tag, boolean isExplicit ) {
		switch ( tag ) {
			case BERTags.SET :
				return ASN1Set.getInstance(this, isExplicit).parser();
			case BERTags.SEQUENCE :
				return ASN1Sequence.getInstance(this, isExplicit).parser();
			case BERTags.OCTET_STRING :
				return ASN1OctetString.getInstance(this, isExplicit).parser();
		}

		if ( isExplicit ) {
			return getObject();
		}

		throw new RuntimeException("implicit tagging not implemented for tag: " + tag);
	}


	public ASN1Primitive getLoadedObject() {
		return this.toASN1Primitive();
	}


	ASN1Primitive toDERObject() {
		return new DERTaggedObject(explicit, tagNo, obj);
	}


	ASN1Primitive toDLObject() {
		return new DLTaggedObject(explicit, tagNo, obj);
	}


	abstract void encode( ASN1OutputStream out ) throws IOException;


	public String toString() {
		return "[" + tagNo + "]" + obj;
	}
}
